US 7252310 B2
A coupler for use in joining two pipes in a butt joint. The coupler includes a band clamp and a split sealing sleeve disposed inside the band clamp for encircling the abutted ends of the pipes. The split sealing sleeve has a tongue-and-groove sealing joint at the confronting free ends of the sleeve. The sealing joint has a member at the mating edges to provide a resilient interference fit of the tongue-and-groove.
1. A pipe coupling for connecting two pipe ends, comprising:
a clamp band extending circumferentially from a first end to a second end;
a tightening mechanism located at said first and second ends of said clamp band, said tightening mechanism including at least one fastener to tighten said clamp band by drawing said first and second ends towards each other; and
a split sealing sleeve located radially inside said clamp band in contact with said clamp band, said split sealing sleeve having first and second circumferential ends in confronting relationship for contact with each other when said sealing sleeve is collapsed circumferentially by tightening of said clamp band, said sealing sleeve including at least one tongue and groove sealing joint, said groove being defined at one circumferential end of the sealing sleeve and said tongue being defined at the other circumferential end of the sealing sleeve, said tongue being disposed opposite said groove for mating with said groove when said sealing sleeve is collapsed circumferentially, the tongue and the groove each having first and second side edges, the first side edge of the tongue and the first side edge of the groove being a first mating-pair of side edges, the second side edge of the tongue and the second side edge of the groove being a second mating-pair of side edges, said tongue having a non-locking interference fit with said groove throughout a range of penetration extending from initial engagement to a point of maximum penetration for both of said mating-pairs, wherein a central portion of at least one of said first side edges is non-parallel relative to a circumferential centerline of said sleeve, said sealing sleeve including a relief slot adjacent one of said first side edges forming a spring member which yields in response to penetration of said tongue into said groove, the width of said tongue before insertion into said groove being greater than the width of said groove, wherein forceful penetration of said tongue into said groove during tightening of said clamp band causes engagement of said non-parallel first side edges with each other and said second side edges with each other which, during further tightening of said clamp, causes said sealing sleeve to deform at said relief slot as said tongue penetrates into said groove.
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3. A pipe coupling as defined in
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This application is a continuation of U.S. application Ser. No. 10/871,118 filed Jun. 19, 2004, now U.S. Pat. No. 7,025,393, which is a continuation of U.S. application Ser. No. 09/886,793 filed Jun. 21, 2001, now U.S. Pat. No. 6,758,501, which claims the benefit of Provisional Patent Application No. 60/213,791 filed Jun. 23, 2000.
This invention relates to pipe couplings; more particularly, it relates to a type of pipe coupling which is especially adapted for joining two pipe ends in a butt joint. This type of pipe coupling is sometimes referred to in the trade as a pipe coupler.
There is a need, especially in the automotive industry, for a pipe coupling for connecting two pipes together in a vehicle engine exhaust system. For example, it is becoming common practice in the repair or servicing of an automobile exhaust system to replace the muffler by cutting the pipe between the muffler and the catalytic converter and attaching a new muffler by use of a special coupling which is herein referred to as a coupler. In this example of use, the coupler must be capable of joining two pipes in a butt joint with a good seal against exhaust gas leakage and which has high pull-apart strength. The use of a butt joint has the advantage of avoiding the need for slotted pipe ends as are commonly used in tail pipe-to-muffler lap joints.
In the prior art, attempts have been made to provide a pipe coupling which would meet the requirements of mechanical strength, exhaust gas sealing properties and long service life required by the automotive industry. However, the prior art leaves much to be desired with respect to the present day requirements.
U.S. Pat. No. 2,227,551 granted Jan. 7, 1941 to Morris describes a pipe coupling which comprises a cylindrical metal sleeve and gasket disposed between a clamping shell and the pipes to be coupled together. The metal sleeve is open with confronting ends which have complementary tongues and recesses which come together when the coupling is tightened.
U.S. Pat. No. 4,056,273 granted Nov. 1, 1977 to Cassel describes a coupling for pipe lap joints which includes a seal ring disposed about the end of the smaller diameter pipe and abutted against the end of the larger diameter pipe. A clamping device has a clamp band which encircles and overlaps the end of the larger diameter pipe and the seal ring. The seal ring includes opposite circumferential ends interengaged with each other, at least one of the seal ring ends having a ramp surface that engages the other seal ring end to move the rings axially relative to each other during clamping of the ring over the inner pipe to thereby provide sealing of the ring between the ring ends.
A general object of this invention is to provide an improved coupler which overcomes certain disadvantages of the prior art.
According to one aspect of the invention, there is provided a pipe coupling for securing a pair of coaxial pipe ends that comprises a split sealing sleeve, clamp band and tightening mechanism. The split sealing sleeve includes an inner surface for contacting an outer surface of at least one of the pipes, an outer surface, a first end having a tongue, and a second end having a groove such that when the first and second ends are drawn together the tongue and groove oppose one another. The tongue includes first and second spring members separated by a relief slot, and the groove includes a plurality of convergent side edges. During formation of a non-locking interference fit the tongue penetrates the groove such that: i) the convergent side edges of the spring members engage the convergent side edges of the groove, ii) the first and second spring members are deflected towards each other, iii) the relief slot is deformed in response to the deflection, and iv) the side edges of the spring members and the groove form a seal against the outer surface of at least one of the pipes.
According to another aspect of the invention, there is provided a pipe coupling for securing a pair of coaxial pipe ends that also comprises a split sealing sleeve, clamp band and tightening mechanism. In this embodiment, the split sealing sleeve includes a tongue with a plurality of side edges, and a groove with a plurality of side edges and at least one arcuate relief slot. During formation of a non-locking interference fit the tongue penetrates the groove such that: i) the side edges of the tongue engage the side edges of the groove, ii) an arcuate side edge of the groove is deflected away from an engaging side edge of the tongue, iii) the arcuate relief slot is deformed in response to the deflection, and iv) the side edges of the tongue and the groove form a seal against the outer surface of at least one of the pipes.
A complete understanding of this invention will be obtained from the detailed description that follows taken with the accompanying drawings.
Referring now to the drawings, two illustrative embodiments of the invention are shown in a pipe coupler especially adapted for use in automotive vehicle engine exhaust systems. It will be appreciated, as the description proceeds, that the invention is useful in many different applications and in a wide variety of embodiments.
The first embodiment of the invention is shown in
The clamp 16, per se, is of known construction and it is described in U.S. Pat. No. 3,905,623 granted to Cassel granted Sep. 16, 1965 the entire disclosure of which is hereby incorporated by reference into this patent specification. As stated above, the clamp 16 includes a clamp band 18 which is formed as an open sleeve and terminates in laterally extending opposed flanges 19 and 21. The clamp also includes a tightening mechanism 24 connected with the clamp band. The tightening mechanism comprises a spline or reaction member 23 disposed between the flanges 19 and 21 of the clamp band 18. A pair of bolts 25 extend through aligned openings in the flanges and reaction member and a force bar 27 against which threaded nuts 29 are seated for actuating the tightening mechanism. The coupler 10 will be described in greater detail below.
The split sealing sleeve 26 is made of sheet metal, suitably stainless steel, and is formed by a stamping operation in flat condition as shown in
The side edges 38 a and 42 a of the groove 36 a are straight except for the corners at the mouth of the groove and at the bottom of the groove each of which is formed with a radius as shown. The side edges of the groove have an angle of convergence, for example, of about 18 degrees, i.e. each side edge extends at an angle of 9 degrees from the center line of the groove. The side edges 52 a and 54 a of the tongue 44 a extend in a straight line between respective corners which are formed with a radius as indicated. When the spring members 46 a and 48 a are in an unstressed or free condition, the side edges 52 a and 54 a have a convergence angle, for example, of about 12 degrees, i.e. each side edge makes an angle of 6 degrees with the center line of the tongue 44 a. The relief slot 50 is suitably of keyhole shape and is disposed symmetrically with reference to the center line of the tongue. The spring members 46 a and 48 a are resilient and constitute cantilever spring arms. The spring members are deflected toward each other in the plane of the tongue when they enter the mating groove and maintain contact with the side edges of the groove 36 a to provide a seal against gas leakage.
The pipes 10 and 12, as manufactured, have a specified nominal diameter with a specified allowable tolerance range within which the actual pipe diameter may vary. Consequently, pipes 10 and 12 may have the same nominal diameter but have a different actual diameter. The greatest difference in diameter would occur when one pipe has an actual diameter at the minimum value of the tolerance range and the other pipe has an actual diameter at the maximum value of the tolerance range.
In use, the coupler 10 in its assembled untightened state is positioned over the abutted ends of pipes 12 and 14 with the juncture of the pipe ends located between the tongue and groove sealing joints 34 a and 34 b. In this position, clamp 16 is ready for tightening by tightening the nuts 29 on the bolts 25. As the tightening of the clamp 16 progresses, the outer ends of the tongues 44 a and 44 b enter the respective grooves 36 a and 36 b and the side edges of the tongues engage the side edges of the respective grooves so that there is sliding frictional engagement therebetween. Assuming that both pipe ends have the same actual diameter, both tongues will enter the respective grooves to the same depth of penetration when the tightening of the clamp 16 reaches its final tightening condition. If the actual diameter of both pipes is at the maximum value of the tolerance range, the penetration will be at a minimum depth with a sealing engagement occurring at points A and B on sealing joint 34 a and at points A and B on sealing joint 34 b as shown in
Assume that the two pipes 12 and 14 have different actual diameters within the allowable pipe diameter tolerance range. In this situation, when final tightening of the clamp 16 is achieved, one side of it will be closed farther than the other side and hence the penetration of the tongue and groove joint on one side of the sealing sleeve 16 will be greater than that on the other side. This will cock the sleeve and, depending upon the cock angle, it may be that only one spring member of each tongue, instead of both, will engage the respective groove to provide sealing engagement. Nevertheless, both sealing joints 34 a and 34 b are effective to seal against leakage because engagement of only one spring member of each tongue with the groove is needed to block gas leakage. Further, because of the resilience of both spring members, the tongue can be compressed during tightening to prevent excessive interference that would inhibit adequate clamp closure. Thus, when the tightening of the clamp 16 reaches the final tightening condition the clamp band 18 is stretched around the sealing sleeve 26 and maintains a clamping force which holds the tongue and groove joints in sealed condition and holds the sealing sleeve sealed against the outer surfaces of the pipes 12 and 14 and the inner surface of the clamp band so that fluid leakage between the ends of the pipes is blocked from escaping to the atmosphere.
A second embodiment of the invention will now be described. The coupler of the second embodiment is of the same construction as the coupler of
The tongue 64 is rectangular with straight side edges and has a width somewhat narrower than the width of the entrance mouth of the groove 62 and somewhat greater than the narrowest width between the spring edges members 74 a and 74 b.
In the use of the coupler implemented with the split sealing sleeve 26′, the single tongue and groove joint 60 is closed concurrently with the tightening of the clamp of the coupler in the same manner as described with reference to the coupler of
Although the description of this invention has been give with reference to particular embodiments, it is not to be construed in a limiting sense. Many variations and modifications of the invention will now occur to those skilled in the art.
As used in this specification and appended claims, the term “for example” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.